Corsair HX850 Platinum (2017) Power Supply Review

1. Introduction2. Bundle & Cabling3. External4. Internal5. Testing Methodology & Results6. Closing Thoughts7. View All Pages

Correctly testing power supplies is a complex procedure and KitGuru have configured a test bench which can deliver up to a 2,000 watt DC load. We run at 35c in our environment to greater reflect warmer internal chassis conditions.

We use combinations of the following hardware:
• SunMoon SM-268
• CSI3710A Programmable DC load (+3.3V and +5V outputs)
• CSI3711A Programmable DC load (+12V1, +12V2, +12V3, and +12V4)
• Extech Power Analyzer
• Extech MultiMaster MM570 digital multimeter
• Extech digital sound level meter
• Digital oscilloscope (20M S/s with 12 Bit ADC)
• Variable Autotransformer, 1.4 KVA

We test in a single +12V configuration.

DC Output Load Regulation
Combined DC Load	+3.3V		+5V		+12V		+5VSB		-12V
	A	V	A	V	A	V	A	V	A	V
85W	0.95	3.34	0.93	5.03	6.03	12.09	0.50	5.01	0.20	-12.03
170W	1.70	3.34	1.68	5.03	12.40	12.08	1.00	5.01	0.20	-12.04
425W	3.02	3.34	3.07	5.02	32.22	12.06	1.50	5.00	0.30	-12.04
640W	4.07	3.33	4.04	5.00	49.00	12.05	2.00	5.00	0.30	-12.04
850W	5.00	3.34	5.23	5.03	65.60	12.02	2.50	5.00	0.50	-12.03

Load regulation is excellent with the rails exhibiting very minor fluctuation under load.

Corsair HX850 Platinum	Maximum Load
	917W

We managed to get the power supply to deliver 917W before it would shut down, delivering around 82W more than rated specifications.

Next we want to try Cross Loading. This basically means loads which are not balanced. If a PC for instance needs 500W on the +12V outputs but something like 30W via the combined 3.3V and +5V outputs then the voltage regulation can fluctuate badly.

Cross Load Testing	+3.3V		+5V		+12V		-12V		+5VSB
	A	V	A	V	A	V	A	V	A	V
760W	1.0	3.34	1.0	5.03	60.0	12.04	0.2	-12.03	0.50	5.01
165W	15.0	3.31	18.0	5.00	2.0	12.09	0.2	-12.03	0.50	5.00

The power supply dealt with the demanding cross load test without issue exhibiting only a little fluctuation. It was tasked with 60A on the +12V rail and it held at 12.04V. The other rails delivered excellent results also.

We then used an oscilloscope to measure AC ripple and noise present on the DC outputs. We set the oscilloscope time base to check for AC ripple at both high and low ends of the spectrum.

ATX12V V2.2 specification for DC output ripple and noise is defined in the ATX 12V power supply design guide.

ATX12V Ver 2.2 Noise/Ripple Tolerance
Output	Ripple (mV p-p)
+3.3V	50
+5V	50
+12V1	120
+12V2	120
-12V	120
+5VSB	50

Obviously when measuring AC noise and ripple on the DC outputs the cleaner (less recorded) means we have a better end result. We measured this AC signal amplitude to see how closely the unit complied with the ATX standard.

AC Ripple (mV p-p)
DC Load	+3.3V	+5V	+12V	5VSB
100W	10	5	10	5
225W	10	10	15	5
450W	10	10	20	5
675W	10	15	25	10
850W	10	15	30	10

Noise suppression results are really impressive, hitting 10mV and 15mV on +3.3V and +5V rails respectively. The +12V rail peaks at 30mV under full load conditions. Fantastic results overall.

Efficiency (%)
100W	87.92
225W	92.21
450W	93.44
675W	92.76
850W	91.71

Efficiency is extremely impressive, peaking at just over 93.4 percent at 50 percent load. This drops to around 91.7 percent at full load.

We take the issue of noise very seriously at KitGuru and this is why we have built a special home brew system as a reference point when we test noise levels of various components. Why do this? Well this means we can eliminate secondary noise pollution in the test room and concentrate on components we are testing. It also brings us slightly closer to industry standards, such as DIN 45635.

Today to test the power supply we have taken it into our acoustics room environment and have set our Digital Sound Level Noise Decibel Meter Style 2 one meter away from the unit. We have no other fans running so we can effectively measure just the noise from the unit itself.

As this can be a little confusing for people, here are various dBa ratings in with real world situations to help describe the various levels.

KitGuru noise guide
10dBA – Normal Breathing/Rustling Leaves
20-25dBA – Whisper
30dBA – High Quality Computer fan
40dBA – A Bubbling Brook, or a Refrigerator
50dBA – Normal Conversation
60dBA – Laughter
70dBA – Vacuum Cleaner or Hairdryer
80dBA – City Traffic or a Garbage Disposal
90dBA – Motorcycle or Lawnmower
100dBA – MP3 Player at maximum output
110dBA – Orchestra
120dBA – Front row rock concert/Jet Engine
130dBA – Threshold of Pain
140dBA – Military Jet takeoff/Gunshot (close range)
160dBA – Instant Perforation of eardrum

Noise (dBA)
100W	<28.0
225W	<28.0
450W	29.8
675W	32.4
850W	33.9

The large fan spins relatively slowly under most load conditions and the unit is not audible until hitting around 500 watts of power demand. In the last 300 watts of load, the fan slowly spins up to around 1,000rpm, which measured 33.9dBa by our meter.

I couldn't hear any coil whine during our tests.

Temperature (c)
	Intake	Exhaust
100W	37	40
225W	38	42
450W	40	49
675W	45	52
850W	47	58

The high levels of efficiency help keep the temperature control system operating with optimisation. Temperatures rise to only a +11 variable at full load.

Maximum load	Efficiency
917 watts	90.6

At 917 watts, the efficiency level measures 90.6%. Not a practical situation to be running 24/7, but worth noting.

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